The present disclosure relates to a gas turbine engine and, more particularly, to fixturing of workpieces such as combustor liner panels therefor.
Gas turbine engines, such as those that power modern commercial and military aircraft, generally include a compressor section to pressurize an airflow, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases.
The combustor section includes a combustor assembly that typically includes a dome assembly that establishes a bluff body to stabilize the flame and a combustor liner assembly attached downstream of the dome assembly. The combustor liner assembly is typically fabricated from individual liner panels welded or bolted together. The combustor liner panels form a substantially closed duct, typically annular, that channels the hot gases of combustion to the turbine section.
The combustor liner assembly is subject to high thermal loads for prolonged periods of time. To survive these conditions, the combustor liner panels are cooled and include various thermal barrier coatings. In one cooling arrangement, a twin wall configuration includes a shell lined with the liner panels attached thereto with studs and nuts. In addition to dilution holes, relatively smaller air impingement holes direct cooling air between the outer shell and the liner panels to cool the backside of the liner panels. This cooling air then exits effusion holes in the liner panels to form a cooling film on the hot side inner surface of the liner panels.
The combustor liner panels are manufactured of high temperature alloys and the hot side inner surface thereof are coated with a thermal barrier coating system. The thermal barrier coating system typically includes a metallic bond coat and a ceramic top coat to insulate the hot side inner surface from hot combustion gases and the associated radiated heat.
The thermal barrier coatings are applied to the liner panels via a spray operation with the liner panels fixtured as mounted in the engine. For one example combustor assembly, ten (10) liner panels are arranged in a circular pattern with about a twenty-five (25) inch diameter with about a two (2) inch axial length. The fixture and parts rotate about a central axis on a turntable while a spray torch traverses back and fourth axially to apply the coating. In order to apply a uniform thermal barrier coating thickness over the hot side inner surface, the spray torch over travels the liner panel edge. Typically, ten (10) parts are coated at a time and about 50% of the spray time is spent in over travel beyond the liner panel edge which wastes significant time and spray coating material.